AI 中文总结
该研究基于哈伯德模型，采用TPSC+方法区分赝能隙区域的真实与虚假费米面，结合DiagMC基准分析其随掺杂和温度的转变，揭示了赝能隙的形成机制及类空穴费米面的低温特性。
AI 中文摘要
针对最近邻哈伯德模型的精确图解量子蒙特卡洛（DiagMC）结果，促使人们对赝能隙开展更深入研究。研究采用改进的两粒子自洽方法（TPSC+），同时分析能量分布曲线（EDC）与动量分布曲线（MDC）。结果表明，费米液体术语在赝能隙区域失效，需区分真实费米面、虚假费米面以及零能准粒子（ZEQ）线：虚假费米面在动量空间存在谱最大值，但在零能处的频率空间存在凹陷；虚假ZEQ线违反标准准粒子条件∂Σ'(k,ω)/∂ω|_{ω=0}<0。赝能隙由临界热自旋涨落驱动，因迈尔明-瓦格纳定理，该涨落出现在二维体系中。 commensurate（公度）涨落首先打开反节点赝能隙，留下真实费弧；随温度降低，费米面演变为类空穴与类电子的虚假费米面。非公度涨落会在对角线附近产生热点，此处赝能隙持续存在至量子临界点（QCP），而在k_AN处，赝能隙在QCP掺杂前消失，该区域的谱存在两个前驱反铁磁（AFM）带，均位于未占据（ω>0）区域。研究以松本谱代理项 -Im[G(k,iπT)]/π的DiagMC结果为基准验证TPSC+：TPSC+在强相互作用区域低估赝能隙的抑制作用，在较低温度或掺杂下可复现DiagMC行为；该代理项等价于热展宽η=πT的谱函数，当πT并非最小能量尺度时会掩盖特征。利用A(k,0)发现，即使在弱耦合下，低温时任意相互作用强度下都会出现类空穴费米面。
英文摘要
Exact diagrammatic quantum Monte Carlo (DiagMC) results for the nearest-neighbor Hubbard model motivate a closer study of the pseudogap. Using the improved two-particle self-consistent approach (TPSC+), we analyze Energy (EDC) and Momentum Distribution Curves (MDC) simultaneously. We show that Fermi-liquid terminology breaks down in the pseudogap regime, requiring a distinction between true and false Fermi surfaces and zero-energy quasiparticle (ZEQ) lines. A false Fermi surface has a momentum-space spectral maximum but a frequency-space depression at zero energy, while a false ZEQ line violates the standard quasiparticle condition $\partial Σ'(\mathbf{k},ω)/\partial ω|_{ω=0}<0$.The pseudogap is driven by critical thermal spin fluctuations, which occur in two dimensions because of the Mermin-Wagner theorem. Commensurate fluctuations first open an antinodal pseudogap, leaving true Fermi arcs. With decreasing temperature, the Fermi surface evolves into hole- and electron-like false Fermi surfaces. Incommensurate fluctuations generate hot spots near the diagonal, where the pseudogap persists to the quantum critical point (QCP), whereas at $\mathbf{k}_{AN}$ it disappears before the QCP doping. There, the spectrum has two precursor antiferromagnetic (AFM) bands, both in the unoccupied ($ω>0$) region. We benchmark TPSC+ against DiagMC results for the Matsubara spectral proxy $-\mathrm{Im}[\mathcal{G}(\mathbf{k},iπT)]/π$. TPSC+ underestimates pseudogap suppression in the strong-interaction regime, reproducing DiagMC behavior at lower temperatures or doping. This proxy is equivalent to the spectral function with thermal broadening $η=πT$, which obscures features when $πT$ is not the smallest energy scale. Using $A(\mathbf{k},0)$, we find that hole-like Fermi surfaces emerge at any interaction strength at low temperature, even at weak coupling.
Comments30 pages, 25 figures
